4age misfiring help needed.

[Cerby86]

Hey every one!

Right so i have a smallport 16V 4age with ST quad throttle bodies running an adaptronic ecu in an ae71.

What happened is this, day before yesterday I was cruising along at 60, no hard revs or anything when suddenly the car developed a massive misfire.
Basically it felt like a plug was badly fouled and a cylinder wasn't firing, i've experienced this before as I took advice from a rapeco employee (first mistake) and bought some bosch platinum plugs which fouled constantly for the first two days I had them but then came right.
The only difference this time was it was making a CHUFFING noise like a REALLY bad exhaust leak at the extractors!
Anyway it turned out that it was backfiring up through the throttle bodies constantly! At first it was happening on cylinder 1 then it swapped to cylinder 3.

So anyway i got it home and pulled the plugs which were covered in crap and put new normal plugs in. didn't fix it.
Then we assumed that one of the leads was dodgy so we tried testing them, one was slightly dodgy but it wasn't the problem. Unfortunately we destroyed that lead during testing so i went out and spent $200!!! on a new set.
didn't fix it! We also pulled apart the distributor cap and cleaned everything and it made no difference.

About this time we noticed that everytime we started the car it would be chuffing out a different throttle body so I decided that it must be the adaptronic. Got the laptop on it late last night and it seemed fine, so im assuming its not that.

Okay so this is were im up to. Its not plugs or leads and the adaptronic is functioning and has the right map in it.
The backfire changes throttle bodies randomly (though it does seem you have to turn it off then start it again to change it).
I haven't checked the timing and Im not sure how to.

What could it be? I thought it might have dropped a valve except its not making any metal noises and it changes throttle bodies randomly.
Any advice would be muchly appreciated! And if JONNY ROCHESTER reads this and i haven't called him yet it would be sweet if he could give me a call so i can pay him to fix it for me again lol!

[sundee]

Timing to advanced, mixtures to lean. Check dizzy is in good condition to.

[Cerby86]

cool, i checked the dizzy as the rotor button and the points seemed fine to me, also definitely not running lean. The tune is pretty rich like rich enough that you can smell it! Which leaves timing. I was thinking maybe the timing belt has slipped or something. I guess i'll have to work out how to check that

[Cerby86]

so checked the timing, and the balancer and gears all line up with their marks. Did a compression test today, 90 psi cylinder 1, 20psi cylinder 2 and 3 and 140 psi on 4!!!
So it wasn't using water or oil before and i only recently had the head gasket done so currently thinking it might be valve spring failure on the intake side!!
Pulling it apart tomorrow so we will see.
Any suggestions on where to get some cheap standard replacement springs?

[sundee]

Did you check the timing with a timing light?
Did you comp test the engine before the new headgasket?
I'd be looking at the headgasket, with comp results like that I'd say the engine is stuffed!
BUT with the backfiring out the TB's their are definatly intake valves stuck open/ not closing.
If it's only doing it on cyl 1 and 3 , and looking at your comp results their is a good chance the engine has other issues ( comp rings, HG, valves)